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  • Synopsis
  • Cluster Configuration Options
  • Azure Availability Zones
  • Azure Fault Domains
  • Integrations
  • More Information

Atlas supports deploying clusters and serverless instances onto Microsoft Azure. This section applies to Atlas database deployments on Azure.

Depending on your cluster tier, Atlas supports the following Azure regions. A check mark indicates support for free clusters, shared clusters, serverless instances, or Availability Zones. The Atlas Region is the corresponding region name used by Atlas processes.

While all of the following regions support M10+ clusters, some regions don't support free clusters, shared clusters, or serverless instances.


Due to their higher cost, it is recommended to use Switzerland West or UAE Central as a secondary disaster recovery (DR) region in a multi-region cluster if necessary.

  • Use Switzerland West in conjunction with Switzerland North.
  • Use UAE Central in conjunction with UAE North.

Each Atlas cluster tier comes with a default set of resources. Atlas provides the following resource configuration options:

Custom Storage Size

The size of the server root volume. Atlas clusters deployed onto Azure use premium SSDs. [1]

RAM Availability

The actual amount of RAM available to each cluster tier might be slightly less than the stated amount, due to memory that the kernel reserves.


As of October 18, 2021, the following Atlas clusters deployed to Azure offer 16,000 IOPS (up from 7,500) and 500 MB/second throughput (up from 250 MB/second):

  • New clusters with 4 TB storage volumes.
  • Existing clusters that you scale up to 4 TB storage volumes.

The following clusters tiers are available:

Cluster Tiers
Default Storage
Default RAM
.5 GB
2 GB
5 GB
8 GB
2 GB
16 GB
4 GB
32 GB
8 GB
64 GB
16 GB
128 GB
16 GB
128 GB
32 GB
128 GB
32 GB
128 GB
64 GB
128 GB
64 GB
256 GB
128 GB
256 GB
128 GB
256 GB
256 GB
256 GB
256 GB
512 GB
384 GB
512 GB
432 GB

Can use this tier for a multi-cloud cluster.

Not available in the following regions:

  • germanywestcentral
  • switzerlandnorth
  • switzerlandwest
Cluster Tier & API Naming Conventions

For purposes of management with the Atlas Administration API, cluster tier names that are prepended with R instead of an M (R40 for example) run a low-CPU version of the cluster. When creating or modifying a cluster with the API, be sure to specify your desired cluster class by name with the providerSettings.instanceSizeName attribute.

Multi-Cloud Low-CPU clusters

Low-CPU cluster tiers (R40, R50, R60, etc) are available in multi-cloud cluster configurations as long as the cluster tier is available for all the regions that the cluster uses.

Workloads typically require less than 2TB.

Atlas configures the following resources automatically and does not allow user modification:

Storage Speed
The input/output operations per second (IOPS) [1] the system can perform. This value is fixed based on the specified custom storage size.
Encrypted Storage Volumes
Azure storage volumes are always encrypted.

Azure maintains multiple data centers within each region. Azure groups the data centers into availability zones, which are separate locations within the region. Maintaining data centers in different physical locations helps Azure tolerate local failures.

Azure availability zones aren't available in all regions. To learn which Azure regions maintain availability zones, see the Azure Region table. In regions where availability zones aren't yet available, Azure uses fault domains to help ensure failure tolerance.

Atlas uses Azure availability zones automatically when you deploy a dedicated cluster to a region that supports them. Atlas splits the cluster's nodes across availability zones. For example, a three-node replica set cluster would have one node deployed onto each zone. A local failure in the Azure data center hosting one node doesn't impact the operation of data centers hosting the other nodes.


Regions with availability zones provide higher uptime for dedicated clusters deployed after September 12, 2019. Clusters deployed before September 13, 2019 to regions that now offer availability zones aren't split across availability zones automatically. To learn more about availability zones, see Azure's documentation.

Each Azure region includes a set number of fault domains for failure tolerance. Fault domains consist of a group of virtual machines that share a common power source and network switch. If you deploy your cluster to a region that doesn't support availability zones, Atlas spreads the nodes across the fault domains instead.

Atlas uses availability sets to deploy clusters across fault domains. For regions that have at least three fault domains (3FD), Atlas deploys clusters across three fault domains. For regions that only have two fault domains (2FD), Atlas deploys clusters across two fault domains.

The Atlas Add New Cluster form marks regions that support 3FD clusters as Recommended, as they provide higher availability.

The number of fault domains in a region has no effect on the number of MongoDB nodes Atlas can deploy. MongoDB Atlas clusters are always made of replica sets with a minimum of three MongoDB nodes.

For general information on Azure fault domains and availability sets, see Availability Sets Overview

If the selected Azure region has at least three fault domains, Atlas clusters are split across three fault domains. For example, a three node replica set cluster would have one node deployed onto each zone.

A 3-node replica set deployed across a 3-fault-domain Azure region.

3FD clusters have higher availability compared to 2FD clusters. However, not all regions support 3FD clusters.

If the selected Azure region has two fault domains, Atlas clusters are split across the two fault domains. For example, a three node replica set cluster would have two nodes deployed to one zone and the remaining node deployed to the other zone.

A 3-node replica set deployed across a 2-fault-domain Azure region.

2FD clusters have a higher chance of loss of availability in the event of the loss of an zone than 3FD clusters. However, where latency or location are a priority, a region that supports 2FD clusters may be preferred.

[1](1, 2) For detailed documentation on Azure storage options, see High-performance Premium Storage and managed disks for VMs

Along with global region support, the following product integrations enable applications running on Azure, such as Azure Virtual Machines, Azure Functions, and Azure Container Instances, to use Atlas instances easily and securely.

For more information on how to use Azure with Atlas most effectively, review the following best practices, guides, and case studies:

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